Vented closure for milk tank manholes



Patented Dec. 12, 1950 UNITED STATES PATENT OFFiCE.

VENTED CLOSURE roe MILK TANK MANHOLES Joseph H. De Frees, Warren, Pa, assignor to Pennsylvania Furnace and Iron Company, Warren, Pa., a corporation of Pennsylvania Application July 9, 1948, Serial No. 37,784

2 Claims. 1

The invention relates to a receptacle closure for the storage or transportation of liquids. It is especially adapted for closures for containers of liquid intended for human consumption, and it will be described with relation to its use on a tank for the transportation of milk from collection points to a dairy.

An object of the invention is to provide novel and improved closure means for a tank manhole, said means being particularly suited for the exclusion from the tank interior of dust or other contamination.

A further object of the invention is to provide a closure of the type defined in the last preceding paragraph, which lends itself readily to perie odic sterilization or simple cleaning operations.

A further object of the invention is to provide a closure having venting means susceptible of being suddenly opened widely, automatically responsive to withdrawal of liquid from the tank interior, whereby to prevent sudden pressure strains on the tank wall.

A further object of the invention is to provide a closure of the nature described, which can be made from a relatively small number of parts at lower cost than the closures heretofore available, and which has entirely adequate structural strength for its purpose.

Other objects and advantages will be apparent from a study of the present specification, in conjunction with the accompanying drawings, in which:

Fig. 1 is a top plan view of a milk tank man hole with a fragmentary showing of adjacent portions of the tank;

Fig. 2 is a vertical sectional view, somewhat enlarged, taken on the line 2-2 of Fig. 1;

Fig. 3 is an end elevational view from the position indicated by the lines 33 of Fig. 2;

Fig. 4 is a side elevational view of the venting means;

Figs. 5 and 6 are sectional views taken on the lines 5-5 and 6-6 of Fig. 4; and

Fig. 7 is a view similar to Fig. 6 but showing the vent partially open; while Fig. 8 is a view similar to Fig. 2, but showing a slightly modified embodiment of the invention.

Figs. 1 to 3 show a fragmentary portion of the top surface Ill of a milk tank which may be a stationary storage tank, though the advantages of the present invention are more fully realized in a transportation tank, since dirt or other contamination is more frequently encountered in road travel.

As is customary. the top of the tank is provided with a manhole ll of substantial size to permit ingress and egress for cleaning purposes, filling the tank,or otherwise. In the embodiment shown in Figs. 1 to 7 the manhole is surrounded by an annular collar or neck l2 having a horizontal, peripheral deck l3 which carries the closure now to be described. The inner edge of the deck which immediately surrounds the manhole supports an annular gasket M provided with a spaced plurality of upwardly opening vent slots [IS on its upper surface.

A dished inner cover l6 has a peripheral flared edge I! disposed to rest on the inner edge of gasket M. The central portion of this cover has an apertured neck l8 provided with an external screw thread adapted to receive a screw cap IS. A flutter valve 2!] has a circular upper edge portion 2! which is gripped between the neck l8 and the cap l9 when the cap is assembled on the neck. The cap [9 has a plurality of vent holes 22 therein.

A flutter valve construction is familiar to those skilled in the art, and is formed from rubber or rubberlike material having a cupped portion Zlla which has a normally closed pair of lips 28b and 200 at the cup bottom. As will be well understood, suction from the tank interior, when liquid is withdrawn through faucets (not shown) near the tank bottom, causes lips 20b and 260' to separate, and venting from the atmosphere proceeds through gasket slots l5, cap apertures 22, and through the opening 24 (Fig. 7) between lips 26b and 200. Normally said lips are biased to closed position, and it will be readily understood that lip-opening pressure is efiective only from above. In milk tank-s there is no substantial development of interior ressure such as is experienced in the storage or transportation of volatile hydrocarbon oils, so that a one way vent is practicable. The flutter valve provides a large venting area, which is immediately efiective upon reduction of inside pressure, and which therefore protects the tank from possible collapse. It also prevents surging milk from passing outwardly through the vent, and prevents escape of the milk if the truck overturns.

Inner cover [6 with the screw cap [9 and flutter valve 2!] may be lifted out readily for cleaning or sterilization.

I have provided an outer cover 26 which is dished, and which has a peripheral flange 27 which seats on the edge of the gasket, outwardly beyond and surrounding inner cover [6. The outer cover is hinged at 28 to a bracket arrangement 29 fixed to deck [3. Diametrically opposed to the hinge are a pair of spaced lugs 30, 3i adapted to receive therebetween a clamping bolt 32 swingably carried on a hinge pin 33 in a bracket 34 which is also fixed on deck l3. A hand wheel 35 can be turned down to tight engagement with lugs 3i), 3!.

The inner cover I6 is maintained tightly in place by means of an adjusting screw 3'! carried in a threaded bushing 38 in outer cover 26. Inward motion of screw 3?, produced by manipulation of hand wheel 39, causes forcible abutment of the screw shank end against cap is. When screw 3'! is adjusted to the desired pressure position, it need not normally be thereafter disturbed, since the attaching means comprising swing bolt 32 can usually be relied on to bring the outer cover, and consequently the inner cover, down to any previously established position.

On consideration of the structure just described it will be apparent that the double closure can be immediately separated for cleaning and sterilizing. Some types of double manhole covers have heretofore, been known and used, but practically without exception the inner cover has been supported from or attached to the outer cover so that it was extremely difficult to get into the space between the covers to clean it. 'The structure shown and described herein permits the omission of hinges and latches from the mare hole closure, and eliminates many projections, recesses, etc; characteristic of prior art structures, where possible contamination could occur.

' Fig. 8 shows another embodiment of the invention. In this embodiment the inner peripheral wall ii of the manhole extends upwardly somewhat above a sloping deck 62. An especially fitted gasket 43 of rubberlike material has an inner curb portion 43a adapted to slidably grip the flanged portion lla of the wall ii, and to support the outer peripheral edge of the inner cover iBa. As in the first described embodiment, the outer periphery of gasket 43 supports the edge of the outer cover 26a. Venting slots 44 may be provided in the gasket.

The sloping deck 42 permits easy drainage of rain, snow, etc'., and downward dislodgement of heavy dirt particles, and the raised curb 43a further prevents contamination of the milk from admission of foreign material.

What I claim is: r

1. Closure means for a liquid-containing tank having in its upper portion a manhole aperture defined by an upwardly projecting peripheral wall, said closure means comprising an annular gasket carried on top of said wall, said gasket" being providedwith spaced, upwardly opening vent slots, an inner dished cover having its peripheral edge resting on said gasket, but otherwise freely removable from said gasket and said peripheral wall, said inner cover having in its central portion an aperture, a screw cap removably seated over said aperture, and having a vent opening therein, normally closed flutter valve means retained in said aperture by said screw cap, and opening inwardly, and being in inward air flow? communication with said vent opening and with said vent slots whereby said flutter valve opens only when the pressure within the tank drops below atmospheric pressure, an outer cover hingedly connected to said wall and spaced outwardly from said inner cover and having its peripheral edge resting on said gasket outwardly beyond the peripheral edge of the inner cover and bridging said upwardly opening vent slots, said outer cover being vided with downwardly movable means adjustably abuttable against the screw cap on said inner cover, said outer cover and said wall being further provided with complementary clamping elements readily engageable and disengageable to respectively close and open said closure means.

2. Closure means as defined in claim 1 where REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 281,608 Browne July 17, 1883 1,838,446 Plews Dec. 29, 1931 2,183,448 Drane Dec. 12, 1939' FOREIGN PATENTS Number Country Date Great Britain Aug. 2, 1940 

